1. Field of the Invention
This invention relates to a mechanical coupler for connecting a rotary driving member to a hub, and in particular, to a mechanical coupler for connecting a magnetic tape recorder motor drive shaft to the hub of a tape reel. Copending application Ser. No. 352,431 discloses a cartridge having splined hubs adapted for use with the mechanical coupler of the present invention.
2. Description Relative to the Prior Art
In magnetic recording, tape continues to play a prominent role as a storage medium for recorded signals. The tape is generally packaged either on individual reels or in cartridges for use with an associated recorder. In the prior art, it is known to mate the tape container to the recorder by means of a large variety of mechanisms and techniques, with the usual requirement that the tape container be readily installed and readily removed. Recorders which use individual supply and takeup tape reels characteristicallY use screw hold down mechanisms or quick disconnect mechanisms for coupling the tape reels to the reel driving motor shafts. In the more commonly used tape cartridges, the supply and takeup hubs are generally splined cylinders which slidingly engage with mating "fingers" of the drive motor spindles in the recorder. The hubs in the cartridge "float" in the cartridge housing so that the tolerances of the cartridge components may be relaxed while still ensuring that the hub will be capable of self alignment when placed over the drive shaft fingers. This allows rapid and simple changing of the inexpensive cartridges, and has proven an adequate means of drive motor-to-cartridge hub connection in the capstan controlled tape transport, where lack of precision in reeling system components generally will not adversely affect the flutter characteristics of the recorder.
A capstanless tape transport, in which the tape speed is completely under control of the transport reeling system is disclosed in U.S. Pat. No. 4,256,996 in the names of Brooks et al. This transport has low flutter characteristics; the tape speed is controlled by means of a microcomputer which maintains constant tape speed by continuous adjustment of the reel motor rotational speed. When such a transport is adapted for use with a removable cartridge, the "looseness" of the mating of the cartridge reel hubs and the drive motor spindle of the recorder, acceptable in the recorders of the prior art employing caPstans for tape speed control, results in unacceptable flutter. The present invention is directed to a quick connect-disconnect mechanical coupler mounted on the drive motor spindle for mating with a splined hub of a cartridge which provides positive and solid engagement, and which does not induce flutter in the tape motion for tape travel in either the forward or reverse directions.